Wireless digital networks, such as networks operating under the current Electrical and Electronics Engineers (IEEE) 802.11 standards, are spreading in their popularity and availability. In a wireless local area network (WLAN) deployment, a number of clients can be connected to the same wireless network via one or more access points. The number and type of smart phones, tablets, laptops and other clients that connect to WLANs continues to rise as new generations of clients hit the market. Such diverse clients with different operating systems and WLAN chipsets often result in a variety of connection speeds roaming behaviors, band preferences, and other capabilities.
Different wireless devices have very different power saving strategies and profiles. Such power saving strategies vary with factors, such as device make, device configuration, change in usage patterns, type of traffic being used (e.g. whether the traffic is broadcast, multicast, or unicast), etc. For example, in a tablet device where the user is actively browsing web data, the device will sleep less often. A delivery traffic indication message (DTIM) informs the clients about the presence of buffered multicast/broadcast data on the access point. It is generated within the periodic beacon at a frequency specified by the DTIM Interval. Every sleeping device on a wireless access point (AP) wakes up at least every DTIM interval to check if there are any pending broadcasts or multicast frames that the AP has buffered for it. This is the time the device has to wake up irrespective of whether the AP has buffered pending unicast frames for the station. In case of devices with less active usage, it is not very useful for the devices to wake up so often to check for pending multicast traffic. On the other hand, some client devices may wake up more frequently. Therefore, DTIM interval control is important for maintaining performance of wireless network for client devices, and at the meantime assuring that the client devices have good power save performance. The DTIM interval is typically configured in terms of number of beacons. For example, if the DTIM interval is configured as 3, then every third beacon will be considered as a DTIM beacon.